Problem with JScrollPane

In my application i'm using a JTextField associated with a JList and a JScrollPane is given to the JList...when i type a name in the JTextField the matched names are displayed in the JList within the JScrollPane...Actually in my application i made the list and pane to be invisible when the window is activted by using a formWindowActivated listener..it will become visible only when i type a name in the JTextField...but whenever i type the name the JScrollPane and the JList are still invisible...but if i click somewhere in the GUI window after entering the first letter of the name the list is becoming visible what can be the problem? Is there any other method to make it visible? is the JList visible already and i can't see it?? There is no MouseListener in my application..... I'm pasting the code below what i used...

Since there's no such class in core Java, any questions regarding it should either be accompanied by the code or asked wherever you got the class.

I'm sorry if i confused you... actually i meant to say WindowListener and the windowActivated(WindowEvent) event in my code...here the form was my JFrame form...
here in this case i just want to display the JList...i'm not bothered about the contents...even if i'm not storing any database values in the JList and i try to make it visible by
typing some values in the JTextField the same problem arises...

i just want to display the JList...i'm not bothered about the contents...even if i'm not storing any database values in the JList and i try to make it visible by
typing some values in the JTextField the same problem arises...